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Chapter 23 The Evolution of Populations. Chapter 23 The Evolution of Populations. Chapter 23 The Evolution of Populations. Modern evolutionary theory is a synthesis of Darwinian selection and Mendelian inheritance Evolution happens to populations A population is defined by its gene pool.
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Chapter 23The Evolution of Populations Modern evolutionary theory is a synthesis of Darwinian selection and Mendelian inheritance Evolution happens to populations A population is defined by its gene pool.
Chapter 23The Evolution of Populations The Hardy-Weinberg Theorem The frequencies of alleles in the population will remain constant if Mendelian segregation is the only process that affects the gene pool. Important definition
Chapter 23The Evolution of Populations The Hardy-Weinberg Equation p2 + 2pq + q2 = 1
Chapter 23The Evolution of Populations The Hardy-Weinberg Equation p q p pp pq q pq qq
Chapter 23The Evolution of Populations p2 + 2pq + q2 = 1 p q p pp pq q pq qq
Chapter 23The Evolution of Populations p2+ 2pq + q2 = 1 p q p pp pq q pq qq
Chapter 23The Evolution of Populations p2 + 2pq + q2 = 1 p q p pppq q pq qq
Chapter 23The Evolution of Populations p2 + 2pq + q2= 1 p q p pppq q pqqq
Chapter 23The Evolution of Populations p2 + 2pq + q2 = 1 p q p pp pq q pq qq
Chapter 23The Evolution of Populations Hardy-Weinberg Equilibrium • Very large population • Totally isolated • No mutations • Random mating • Equal reproductive success.
Chapter 23The Evolution of Populations Microevolution • Very large population • Totally isolated • No mutations • Random mating • Equal reproductive success
Chapter 23The Evolution of Populations Microevolution • Genetic drift • Totally isolated • No mutations • Random mating • Equal reproductive success
Chapter 23The Evolution of Populations Microevolution • Genetic drift • Migration • No mutations • Random mating • Equal reproductive success
Chapter 23The Evolution of Populations Microevolution • Genetic drift • Migration • Mutations • Random mating • Equal reproductive success
Chapter 23The Evolution of Populations Microevolution • Genetic drift • Migration • Mutation • Natural selection and sexual selection
Chapter 23The Evolution of Populations Microevolution Generation-to-generation change in allele frequencies. Important definition
Chapter 23The Evolution of Populations Genetic variation
Chapter 23The Evolution of Populations Genetic variation Within populations and between populations.
Chapter 23The Evolution of Populations Genetic variation Produced by:
Chapter 23The Evolution of Populations Genetic variation Produced by: • Mutations
Chapter 23The Evolution of Populations Genetic variation Produced by: • Mutations • Sexual recombination.
Chapter 23The Evolution of Populations Genetic variation Preserved by:
Chapter 23The Evolution of Populations Genetic variation Preserved by: • Diploidy
Chapter 23The Evolution of Populations Genetic variation Preserved by: • Diploidy • Balanced polymorphism • Heterozygote advantage • Frequency-dependent selection.
Chapter 23The Evolution of Populations Important definition Fitness The relative contribution an individual makes to the next generation’s gene pool.
Chapter 23The Evolution of Populations Fitness Selection favors genotypes by acting on phenotypes.
Chapter 23The Evolution of Populations Kinds of selection
Chapter 23The Evolution of Populations Kinds of selection • Directional • Stabilizing • Diversifying.
Chapter 23The Evolution of Populations Disadvantages of sexual reproduction:
Chapter 23The Evolution of Populations Disadvantages of sexual reproduction: • Only half the population can give birth. • Only half the offspring can give birth.
Chapter 23The Evolution of Populations Advantages of sexual reproduction:
Chapter 23The Evolution of Populations Advantages of sexual reproduction: • Genetic variation provides resistance to disease. • This is enough to overcome the disadvantages.
Chapter 23The Evolution of Populations Sexual selection leads to sexual dimorphism. • Intrasexual selection: • Intersexual selection:
Chapter 23The Evolution of Populations Sexual selection leads to sexual dimorphism. • Intrasexual selection: Competition between members of same sex. • Intersexual selection: Choosiness for mates.
Chapter 23The Evolution of Populations Evolution has its limits. • Evolution builds on existing structures • Adaptations are compromises. • Chance is a powerful force • Existing alleles can be favored, but new ones cannot be made on demand. .
